In a mobile communication system, a mobile communication channel is a multipath fading channel. A signal transmitted in the mobile communication system can reach a reception terminal only by being directly transmitted, reflected and scattered etc. through multiple propagation paths. In addition, with the mobility of a mobile CMMB terminal, the burden, delay and phase of the signal on various propagation paths change anytime and anywhere. Therefore, a level of the signal received by the receiver is unstable, and these multipath signals with different phases are added together to form fading. The change in the amplitude of the added signals complies with a Rayleigh distribution, and therefore, it is referred to as Rayleigh fading. When the Rayleigh fading rapidly changes with time, it is referred to as “fast fading”. The shadow fading is a slow change in a median of signal due to the influence of the terrain (for example, block of a building etc.).
At present, diversity reception is generally used to overcome multipath fading. With such method, the receiver can make a decision on multiple received signals with the same information and independent fading characteristics after conducting a merging process. Wherein, spatial diversity can be used to reduce the influence of slow fading, i.e., the signal is transmitted and received respectively using several independent antennas or at different positions to ensure independence of fading among various signals. As the geographical environments are different in the process of transmitting these signals, the fading of various signals is also different. If a selective merging technology is used to select a stronger output therefrom, the influence of the factors such as terrain on the signals can be reduced.
However, the existing method for achieving diversity reception reduces the mobile performance of the CMMB reception terminal.